274 botanical gazette. [ November, 



moist weather or when kept in a damp chamber the coni- 

 diophores become indefinitely elongated and irregularly 

 branched : but the single dichotomous form is characteristic 

 of the species. Towards their extremities the conidiophores 

 are furnished with the successive vesicular swellings, mark- 

 ing the point of proliferation from the insertion of previously 

 formed conidia, which are characteristic of the genus. 



In its large size the species approaches the European P. 

 Cactorum ; but, although I have not been able to examine 

 specimens of this species, it seems to differ essentially from 

 the one under consideration, both in its larger size and mode 

 of branching. Prof. Farlow informs me that a specimen 

 distributed in the Mycotheca Mar chic a on Brassica, and 

 labelled "P. omnivoVa " (a form which, together with P. 

 Fagi and P. Sempervivi, has been shown by de Bary 1 to 

 belong to a single species, P. Cactorum) approaches the 

 present species in its luxuriant habit; but on examination 

 proves to be merely Peronospora parasitica. 



Pliytophthora Phaseoli nov. sp. 



My 



the host by irregular haustoria. Conidiophores slightly swol- 

 len at their point of exit through the stomata, arising singly 

 or one to several in a cluster; simple or once dichotomously 

 branched, and once to several times successivelv inflated 

 below their apices. Conidia oval or elliptical, with truncate 

 base and papillate apex ; 35-50^ X 20-24/*. Germination by 

 zoospores, usually fifteen in number, or rarely by a simple 



hypha of germination. Oospores unknown. 



{Phaseoli 



luuatus), New Haven, Connecticut, September and October 



JV 



Notes on North American Umbellifera. I. 



JOHN M. COULTER AND J. N. ROSE. 



The series of papers bearing the above title are intended 



)lementary to our Revision of North American Um- 



Caucalis microcarpa If. & A. has been sent by C. R- 



Orcutt from Lower California. 



/ ferce . 



*Bot. Zeit. 1881, pp. 251-26 



